What are the green sacs on my yucc a and how do I effectively remove a plant?

My cousin had planted some yucc a plants in front of house to thin his out. They are a beautiful plant but they did not survive where he placed them. Instead they have now invaded my roses. I removed the ones from my roses. It took me all day. I gave them to my sister. My roses bloomed like crazy. YAY!! Now the yucca s grew back. No more roses again. Boo hoo. The roses have been there at least 80 years. It is how long my grandpa owned the house. These Yuccas are turning me into one bushed Gardner!

Those will be flower heads! They will turn into seeds and spread. These will be hard to control, as they spread from underground tubers. The only way to get rid of these without harming the roses will be to remove them by hand each time you see one come up. It will take a few years, more than likely. Once these get established, they will take over an area very quickly.